It is known, in the bakery, to use bakers' yeast in the form of a bakers' yeast cream.
Bakers' yeast cream is understood as meaning a liquid suspension, typically an aqueous suspension, of live bakers' yeast cells, said suspension having a dry matter content of at least 12% by mass and generally of between 12 and 50% by mass (broad definition of yeast cream). The bakers' yeast cream preferably meets the normal definition of yeast cream, i.e. it has a dry matter content of between 12 and 25% by mass, and more preferably of between 15 and 22% by mass. However, the present invention is also useful for bakers' yeast creams with a high dry matter content, that is to say of at least 25% by mass, such as, in particular, the high-density bakers' yeast creams containing one or more osmotic agents, for example food salts and polyhydroxy compounds. High-density bakers' yeast creams of this kind, which may in particular have a dry matter content of 25 to 48% by mass, or of 25 to 46% by mass, are known and are described, for example, in WO 91/12315 and WO 03/048342.
It is known in particular in the bakery to use baker's yeast creams.
A stable yeast cream is a yeast cream retaining its homogeneity for a sufficiently long time so that it may be conserved without stirring, during its storage and possibly its transport, until it is used in the preparation of a dough for baking.
A stabilized bakers' yeast cream is a bakers' yeast cream containing one or more food stabilizers which delay or prevent decantation of the yeast cells of the suspension. Due to the presence of said food stabilizer or stabilizers in the suspension, the yeast cream retains its homogeneity longer when it is conserved without stirring. Among the various food stabilizers that can be used to stabilize yeast cream, can be mentioned gums, such as xanthan gum, and thermally and/or chemically modified starches, such as acetylated distarch adipate corresponding to the definition of modified starch E1422. Such stabilized yeast creams are described, for example, in EP-A-0 792 930.
The stable yeast cream is preferably a stabilized yeast cream.
The homogeneity of the yeast cream, that is to say the substantial absence of a concentration gradient of dry matter in the cream, is an important property for the baker.
Indeed, the main advantage for the baker in using a bakers' yeast cream is that it permits simple dosing by virtue of its liquid form. However, this dosing of the yeast can be precise and reliable only if the yeast cream is homogeneous. Lack of homogeneity, or, in other words, the presence of a perceptible concentration gradient of dry matter in the bakers' yeast cream, leads to errors in the quantity of yeast cells measured out in successive cream-dosing operations for introduction of said bakers' yeast cream into doughs, and thus leads to variations in the quality of the baked products prepared with these doughs.
The stable or stabilized bakers' yeast cream can also comprise one or more other ingredients, such as bread improvers (oxidizing agents, reducing agents, enzyme preparations, emulsifiers) and/or preserving agents and/or other technological auxiliaries such as polyols.
An installation for dosing of stabilized bakers' yeast cream has been proposed in EP-A-0 792 930. Such an installation is useful in particular for industrial bakeries with a yeast cream consumption of at least 300 liters per week, typically of at least 500 liters per week.
An installation of this type for dosing bakers' yeast cream is generally not suitable for bakeries in which the consumption of yeast cream does not exceed 150 liters per week. Indeed the costs associated with the installation, use and maintenance of this installation for dosing yeast cream, make using such an installation unprofitable for a small-scale bakery.
It has also been proposed to supply stabilized yeast cream in small packages, for example of 0.1 liter or more.
Although such packages may prove useful for domestic use, they are not at all practical for the baker who regularly and almost continuously requires relatively small quantities of yeast cream.
Since stable or stabilized bakers' yeast cream is a highly perishable food product, it must be kept cool.
The temperature in a baker's workshop, where the doughs are prepared, generally rises to at least 15° C. Such a temperature does not permit adequate conservation of the stable or stabilized yeast cream, because it leads to an acceleration in the loss of viability and fermentative power of the yeast and in the growth of microbial contaminants which may be present. The baker therefore has to store the yeast cream in a refrigerator and take it out of the refrigerator when introducing the yeast cream into the kneader for the preparation of a dough.
Different options may be envisaged for the type of the small packages mentioned above.
According to a first option, the stable or stabilized yeast cream is packaged in quantities corresponding to the amount of yeast cream needed to prepare a single batch of dough. This option, which may be convenient for domestic use, is not convenient for bakers because it leads to a higher price for the cream and deprives bakers of any flexibility in their productions, which are generally multiple.
According to another option, the yeast cream is packaged in quantities corresponding to the amount of yeast cream needed to prepare a series of batches of dough.
The baker then has to either leave his workshop on each occasion and go into his refrigerator in order to measure out the desired amount of yeast cream or, has to remove the package of yeast cream from his refrigerator, measure out the desired amount of yeast cream and immediately return the package of yeast cream to the refrigerator. These operations are in general rather impractical and inefficient for the professional.
In the case of packaging in quantities corresponding to the amount of yeast cream needed to prepare a series of batches of dough, the baker will naturally tend to remove the package of stable or stabilized yeast cream from his refrigerator and leave it longer than is strictly necessary in his workshop and, consequently, at temperatures leading to accelerated perishing of the yeast cream contained therein, with all the ensuing problems of poor quality of the baked products and of additional costs due to the quantity of yeast cream to be discarded.